Comparison of performance limits for carbon nanoribbon and carbon nanotube transistors

Carbon-based nanostructures promise near ballistic transport and are being intensively explored for device applications. In this letter, the performance limits of carbon nanoribbon (CNR) field-effect transistors (FETs) and carbon nanotube (CNT) FETs are compared. The ballistic channel conductance and the quantum capacitance of the CNRFET are about a factor of 2 smaller than those of the CNTFET because of the different valley degeneracy factors for CNRs and CNTs. The intrinsic speed of the CNRFET is faster due to a larger average carrier injection velocity. The gate capacitance plays an important role in determining which transistor delivers a larger on current. (c) 2006 American Institute of Physics.